1. Field of the Invention
The present invention relates to the field of producing integrated devices by attaching one or more separately produced components on a surface of a substrate.
2. Description of the Related Art
Electronic systems are composed of logic blocks, i.e. processors and memories, as well as communication buses. A significant portion of the loss of performance in such electronic systems results from the propagation time of electrical signals in interconnections between these components. A Systems-on-Chip (SOC) approach allows a reduction of these interconnection lengths in that the components of the system are cohabited on a single substrate, preferably by integrating all the components into a single chip. Different functional components such as RF MEMS, optical MEMS, III-V circuits, SiGe circuits, and the like, usually are produced using different non-compatible process technologies such that an integration on the same substrate is complex to achieve.
Presently, the options to achieve wafer scale level integration include: first, place separate components side by side, i.e. laterally, second, is to stack the components on a main surface of a base substrate or on top of each other to achieve a vertical integration, and third, a combination of lateral and vertical integration.
A conventional technique for stacking one or more components on a device or on a substrate includes, for example, allowing for transferring components from a source substrate to a receiver surface of the receiving device or the receiving substrate by aligning the source substrate carrying the components with the receiver surface, by bringing the components of the source substrate into contact with the receiver surface, by releasing the components from the source substrate such that the components are placed on the receiver surface and by finally removing the source substrate.
One important precondition to apply such a process is that when the source substrate is aligned with the receiver surface all of the components to be placed may come into full contact with respective contact areas of the receiver surface. This substantially requires that the respective contact areas of the receiver surface, onto which the components are to be placed, and the contact surface of the components, to be brought into contact with the areas of the receiver surface, correspond to each other. Preferably, both the areas of the receiver surface and the contact surfaces of the components to be attached thereon are planar and in parallel with a lateral dimension of the receiver surface. In other words, after bringing the components of the source substrate into contact with the receiver surface, the contact surfaces of the components substantially fully abut on the respective contact areas of the receiver surface.
The stacking of a plurality of devices onto each other using a transfer technology as explained above is generally realized when the contact surface of the devices attached on the source substrate and the contact areas of the receiver surface are at a horizontal uniform level. However, the application of components at wafer scale level on receiver substrates having a non-even topography using the above process is restricted.
U.S. Pat. No. 7,071,031 discloses an arrangement in which a MEMS structure is attached to the surface of a chip by means of metal stud connected to an anchor portion of the MEMS structure.
In “CMOS compatible wafer-level microdevice-distribution technology” by R. Guerre et al., Transducers 2007 International, page 2087-2090, June 2007, a device integration method is disclosed using AFM cantilevers as a test vehicle and distributing those to receiver wafers.
U.S. Application No. 20030087476 discloses a manufacturing process for displays in which a light emitting element is transferred by peeling the element from one substrate and bonding the removed element on another substrate using a cementing layer.
In U.S. Application No. 20070164463, a pattern transfer device is disclosed for usage in optical disk manufacturing processes. The device presses a transfer die having a concavo-convex pattern against a transfer target on a substrate to transfer the concavo-convex pattern onto a surface of the transfer target.
In U.S. Application No. 2006035164, a method for the duplication of microscopic patterns from a master to a substrate is disclosed in which a replica of a topographic structure on a master is formed and transferred when needed onto a receiving substrate using one of a variety of printing or imprint techniques, and then dissolved.
In U.S. Application No. 20060180595, a wafer that comprises a plurality of dies is attached to a surface of a tape structure. A grid of grooves is formed in the wafer to separate the plurality of dies on the surface of the tape structure. A portion of the tape structure that is accessible through the grooves of the grid is caused to harden into a grid shaped structure. The grid shaped structure removably holds the plurality of dies.
U.S. Application No. 200301140001 discloses the formation of a semiconductor device that involves bonding a donor substrate to a receiving substrate via a donor mesa, and removing a bulk portion while leaving the transferred layer of the donor substrate bonded to the receiving substrate.
In the article, “Wafer-Level 3D Integration Technology Platforms for ICs and MEMS”, F. Niklaus, et al., describe adhesive wafer bonding for integrating high performance transducers with electronic circuits for arrayed highly-integrated sensor and actuator components. (http://www.ee.kth.se/php/modules/publications/reports/2005/IR-EE-MST—2005—001.pdf accessed on Nov. 21, 2007.)
So far, no practical solution has been shown for transfer of components to a receiver surface having uneven topography, such as, areas on the receiver surface having different levels with respect to the lateral dimension of the receiver surface, cavities, and tilted areas.
Therefore, it is one object of the present invention to provide a method for producing integrated devices having one or more separately made components attached on a receiver surface of a receiving device or a receiving substrate wherein the components can be attached even if the receiver surface has an uneven topography.